chore: use non-blinking software block cursor in TUI

[gnodet]

Summary

• Replace the hardware terminal cursor in ShellPanel with a software-rendered reversed-video cursor that does not blink. The hardware cursor's blink timer resets on every TamboUI frame redraw, causing it to appear half-shown on each keypress.
• Replace the blinking half-block (▌) cursor in CaptionOverlay with a non-blinking full-block (█) character.
• The software cursor renders the character at the cursor position with reversed style, matching the approach already used by AiPanel and similar to how Claude Code renders its cursor.

Changes

• ShellPanel: Add convertRow(buffer, offset, width, cursorCol) overload that emits the cursor column as a single reversed-video span. Pass cursor coordinates from renderLiveView instead of using frame.setCursorPosition(). Remove lastCursorX/lastCursorY tracking fields.
• CaptionOverlay: Replace ▌/space blink toggle with static █.
• ShellPanelTest: Add 6 tests for cursor rendering (middle, start, end, null codepoint, no cursor, bold run split).

Test plan

• All 525 TUI module tests pass
• New cursor rendering tests cover edge cases (cursor at start/middle/end, null cell, bold text, no-cursor sentinel)
• Manual: open camel monitor TUI, open shell panel (F6), verify cursor is a solid non-blinking reversed block
• Manual: verify cursor moves correctly with arrow keys, Home/End
• Manual: test CaptionOverlay inline input shows non-blinking block cursor

Claude Code on behalf of Guillaume Nodet

[github-actions]

🌟 Thank you for your contribution to the Apache Camel project! 🌟
🤖 CI automation will test this PR automatically.

🐫 Apache Camel Committers, please review the following items:

• First-time contributors require MANUAL approval for the GitHub Actions to run
• You can use the command /component-test (camel-)component-name1 (camel-)component-name2.. to request a test from the test bot although they are normally detected and executed by CI.
• You can label PRs using skip-tests and test-dependents to fine-tune the checks executed by this PR.
• Build and test logs are available in the summary page. Only Apache Camel committers have access to the summary.

⚠️ Be careful when sharing logs. Review their contents before sharing them publicly.

[github-actions]

🧪 CI tested the following changed modules:

• dsl/camel-jbang/camel-jbang-plugin-tui

---

🔬 Scalpel shadow comparison — Scalpel: 2 tested, 1 compile-only — current: 2 all tested

Maveniverse Scalpel detected 3 affected modules (current approach: 2).

⚠️ Modules only in Scalpel (1)

• camel-launcher

Skip-tests mode would test 2 modules (1 direct + 1 downstream), skip tests for 1 (generated code, meta-modules)

Modules Scalpel would test (2)

• camel-jbang-plugin-tui
• camel-launcher-container

Modules with tests skipped (1)

• camel-launcher

ℹ️ Shadow mode — Scalpel observes but does not affect test execution. Learn more

All tested modules (3 modules)

• Camel :: JBang :: Plugin :: TUI
• Camel :: Launcher
• Camel :: Launcher :: Container

---

⚙️ View full build and test results

[davsclaus]

LGTM